Russia fired missiles and drones into apartment buildings in Kyiv for the second time in a week Monday, killing at least 26 people on the eve of a crucial NATO summit, Ukrainian authorities said.

The attack hit just days after another Russian strike killed more than 30 people in the Ukrainian capital.

President Volodymyr Zelensky decried the "brutal strike", saying that "the Russians' tactics are unchanged: to inflict as much pain and damage as possible on Ukrainians and on Ukraine."

In the northeastern city of Sumy, Russian drone strikes killed two people on Monday, the Ukrainian regional military administration said.

Zelensky -- expected to hold talks with US counterpart Donald Trump at the NATO summit in Turkey -- pleaded for the alliance to boost Ukraine's air defence against Russia's ballistic missiles.

He said Kyiv was successful in shooting down drones and cruise missiles but had "not enough means of defence" against hard-to-intercept ballistic missiles.

"It is simply absurd that in the modern world, production has still not been organised to the extent that is necessary to protect people from ballistic terror," he said in the aftermath of the strikes.

He said Kyiv expected "decisions" on Ukrainian air defence at the NATO summit in Turkey.

Earlier, NATO chief Mark Rutte said in Ankara: "Allies and NATO partners must continue to ensure Ukraine gets what it needs."

The morning strike punched a crater into a multi-storey apartment block in Kyiv's Podilsky district, ripping its floors in two.

AFP reporters heard more than 10 explosions during a ballistic missile alert at night, with flashes in the sky as the blasts rang out.

Eighteen people were killed in the capital, and another eight in Vyshneve, a town just outside Kyiv, authorities said.

Officials said more than 100 people were wounded in the strikes.

It was the second attack in a week in which Russia deployed ballistic missiles, with Kyiv appealing for allies to send missiles for US-made Patriot air defence systems.

Russia fired 68 missiles and 351 attack drones, Zelensky said.

Two more people were killed in the southern city of Zaporizhzhia, Kyiv said.

'Need to pray'
Emergency employees worked through destroyed apartments and carried out bodies on white sheets.

A woman screamed as rescuers pulled a body from the eighth floor of a building.

"I felt the need to pray," Oleksandr Kolomiyets, 60, told AFP outside the destroyed building in the Podilsky district.

Anna Misko, a 36-year-old who recently returned to Ukraine, said she and her child had survived by a "miracle" as they went down to the ground floor of the building.

Russia "wants to destroy us", she said, adding that "there is no place" that is safe in Ukraine.

Russia's defence ministry said the "massive strike" had targeted what it described as "military-industrial enterprises", fuel and energy facilities in several Ukrainian regions.

Kyiv resident Oleksandr Seleznyov said the war had reached a "new phase".

"I think the Russians want to make Kyiv uninhabitable for civilians."

Around 30 residential buildings in Kyiv were hit, officials said.

In the Kyiv region of Vyshneve, authorities said they evacuated around 500 people after the strikes.

Zelensky said the situation there was "difficult because of a secondary detonation", demanding that security services clarify what happened.

Kyiv strikes Siberia refinery
While Kyiv reeled from the attack, the Ukrainian army said it had struck an oil refinery in Russia's Omsk region, around 2,500 kilometres (1,550 miles) from Ukraine's border, in one of its deepest hits during the almost four-and-a-half-year war.

Zelensky said Kyiv used "upgraded Fire Point drones" -- Ukrainian long-range drones -- for the strike.

"Siberia is now also within reach of Ukrainian precision," he said.